The aim of the project is to investigate some of the cognitive processes utilized by infants in their processing of adults' manual actions. Individual studies in the project address four specific objectives: (1) to provide more detailed experimental confirmation of previous research indicating that infants at 9 months of age processed mothers' manual actions with objects as transformations of a static object; (2) to investigate 9- and 16-month-olds' sensitivity to the productive and perceptual complexity of actions observed; (3) to ascertain whether infants' sensitivity to the productive complexity of actions is related to their capacity for spontaneously generating complex actions; finally, (4) to establish whether infants' characteristic modes of processing information generated by adults' actions are related to the frequency and variety of mothers' manual actions during object-centered interactions. To date, the first specific research objective has been met, and the findings provide strong support for the hypothesis that the younger infants process adults' manual actions as transformations of a static object. Thus, the processing of an adult action is prolonged in 9-month-olds, but not in 16-month-olds, following prior exposure to the object in a static state. Most of the data addressing the remaining three issues are in hand, and they are currently being coded and analyzed.